Microsurgical probe

ABSTRACT

Microsurgical probes having a distal tip with a flat outer surface and a flat inner surface, and methods of forming such probes, are disclosed.

This application is a divisional application of U.S. application Ser.No. 11/520,316 filed Sep. 13, 2006 which claims the priority of U.S.Provisional Application No. 60/725,526 filed Oct. 11, 2005.

FIELD OF THE INVENTION

The present invention generally pertains to microsurgical probes andmore particularly to ophthalmic microsurgical probes such as vitrectomyprobes.

DESCRIPTION OF THE RELATED ART

Posterior segment ophthalmic surgical procedures generally require thecutting and/or removal of the vitreous humor, a transparent jelly-likematerial that fills the posterior segment of the eye. The vitreoushumor, or vitreous, is composed of numerous microscopic fibers that areoften attached to the retina. Therefore, cutting and removal of thevitreous must be done with great care to avoid traction on the retina,the separation of the retina from the choroid, a retinal tear, or, inthe worst case, cutting and removal of the retina itself.

The use of microsurgical cutting probes in posterior segment ophthalmicsurgery is well known. Such vitrectomy probes are typically inserted viaan incision in the sclera near the pars plana. The surgeon may alsoinsert other microsurgical instruments such as a fiber opticilluminator, an infusion cannula, or an aspiration probe during theposterior segment surgery. The surgeon performs the procedure whileviewing the eye under a microscope.

Conventional vitrectomy probes typically include a hollow outer cuttingmember, a hollow inner cutting member arranged coaxially with andmovably disposed within the hollow outer cutting member, and a portextending radially through the outer cutting member near the distal endthereof. Vitreous humor is aspirated into the open port, and the innermember is actuated, closing the port. Upon the closing of the port,cutting surfaces on both the inner and outer cutting members cooperateto cut the vitreous, and the cut vitreous is then aspirated away throughthe inner cutting member. U.S. Pat. Nos. 4,577,629 (Martinez); 5,019,035(Missirlian et al.); 4,909,249 (Akkas et al.); 5,176,628 (Charles etal.); 5,047,008 (de Juan et al.); 4,696,298 (Higgins et al.); and5,733,297 (Wang) all disclose various types of vitrectomy probes, andeach of these patents is incorporated herein in its entirety byreference.

During posterior segment ophthalmic surgery, it is generally desirableto remove as much of the overlying vitreous as possible prior to anyprocedure to repair the underlying retina. However, a surgeon is limitedin how close to the retina he or she can dispose a conventionalvitrectomy probe due to the geometry of the probe tip and the cuttingport. Therefore, a need continues to exist for an improved vitrectomyprobe that does not suffer from the above-described limitations.

SUMMARY OF THE INVENTION

One aspect of the present invention is a microsurgical probe. The probecomprises a tubular body having an inner bore, a port providing accessto the inner bore, and a closed distal tip. The distal tip has a flatinner surface.

Another aspect of the present invention is a first method of forming amicrosurgical probe. A tubular needle is disposed within a collet. Thecollet and the needle are rotated at high speed. A tool having agenerally flat distal surface with a spherical projection thereon isprovided. An edge of a distal end of the needle is contacted with thespherical projection. The tool is moved across the distal end of theneedle from the edge to slightly past a centerline of the needle so thatthe distal end of the needle is formed into a closed distal tip having aflat outer surface and a flat inner surface.

Another aspect of the present invention is a second method of forming amicrosurgical probe. A distal end of a tubular needle is disposed incontact with a sheet of foil. A compressive force is imparted to theneedle and the foil. An electrical impulse is sent between the needleand the foil so that the foil is welded to the needle. The needle isdisposed in a punch die, and the needle is punched through the foil sothat a closed distal tip having a flat outer surface and a flat innersurface is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and forfurther objects and advantages thereof, reference is made to thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a side, sectional, fragmentary view of the distal portion of avitrectomy probe according to a preferred embodiment of the presentinvention;

FIG. 2 is a side, sectional, fragmentary view of the distal portion of aconventional vitrectomy probe;

FIG. 3 is a side, sectional, fragmentary view of the distal portion of asecond, conventional vitrectomy probe;

FIGS. 4A-4C schematically illustrate a process to manufacture thevitrectomy probe of FIG. 1 according to a preferred embodiment of thepresent invention;

FIG. 5 is a enlarged, fragmentary, sectional, schematic view of apreferred tool for the process of FIGS. 4A-4C; and

FIGS. 6A-6C schematically illustrate a second process to manufacture thevitrectomy probe of FIG. 1 according to a preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiments of the present invention and their advantagesare best understood by referring to FIGS. 1 through 6 of the drawings,like numerals being used for like and corresponding parts of the variousdrawings.

FIG. 1 shows the distal portion of a vitrectomy probe 10 according to apreferred embodiment of the present invention. Probe 10 generallyincludes a tubular body 12 having an inner bore 14, a closed distal tip16, and a port 18 providing access to inner bore 14. Tubular body 12 ispreferably made of stainless steel. An inner cutting member (not shown)longitudinally reciprocates within inner bore 14 so as to cut tissueaspirated into inner bore 14 via port 18 by a surgical console (notshown). Distal tip 16 has a flat outer surface 16 a and a flat innersurface 16 b. Probe 10 preferably has a 20 gage to 25 gage diameter.

FIGS. 2 and 3 show the distal portions of conventional vitrectomy probes22 and 24, respectively. Probes 22 and 24 each generally include atubular body 26 having an inner bore 28, closed distal tips 30 and 30 a,and a port 32 providing access to inner bore 28. Tubular body 26 ispreferably made of stainless steel. An inner cutting member (not shown)longitudinally reciprocates within inner bore 28 so as to cut tissueaspirated into inner bore 28 via port 32 by a surgical console (notshown).

Distal tip 30 has a convex, spherical outer surface 34 and a concave,spherical inner surface 36. Distal tip 30 is manufactured using aconventional spin forming process. In conventional spin forming, tubularneedle stock is rotated and a tool having a generally concave distal endis brought into contact with the end of the needle. The force of thetool on the rotating needle closes the end of the tube and creates adistal tip 30 having a spherical geometry.

Distal tip 30 a has a flat outer surface 42 and a convex, sphericalinner surface 44. Distal tip 30 a is manufactured using a conventionalbead (or TIG) welding process. In conventional bead welding, anelectrode is placed above the end of tubular needle stock and anelectric current is passed between the needle and the electrode. A beadof material is formed on the needle end, creating a closed distal tip 30a having a spherical geometry. Secondary machining operations areperformed on outer surface 42 to make it flat. However, inner surface 44retains a convex, spherical shape because the inside weld flash isdifficult to control.

As is explained in greater detail hereinbelow, flat outer surface 16 aand flat inner surface 16 b are preferably formed using an improved spinforming process, or a resistance welding process. Flat outer surface 16a and flat inner surface 16 b result in distal end 18 a of port 18 beinga smaller distance 20 from outer surface 16 a than compared to thedistance 40 between distal end 38 of port 32 and outer surface 34 ofconventional probe 22, or the distance 48 between distal end 46 of port32 and outer surface 42 of conventional probe 24. Flat inner surface 16b also allows distal end 18 a of port 18 to be disposed in a nearlycoplanar arrangement with inner surface 16 b. In contrast, distal end 38of port 32 of conventional probe 22 is offset from its inner surface 36due to the concave, spherical geometry of inner surface 36. Similarly,distal end 46 of port 32 of conventional probe 24 is offset from itsinner surface 44 due to the uncertain tolerances of the inside weldflash in the bead welding process. Distance 20 is preferably about 0.006inches to about 0.016 inches, and is most preferably about 0.006 inchesto about 0.011 inches. Distal end 18 a of port 18 is preferably disposedabout 0.003 inches to about 0.005 inches from inner surface 16 b. Byminimizing distance 20, a surgeon may dispose probe 10 closer to theretina without contacting the retina. Thus, with probe 10 the surgeonmay remove more of the overlying vitreous before performing a procedureto repair the underlying retina than with conventional probes 22 or 24.

FIGS. 4A-4C and FIG. 5 schematically illustrate a preferred, improvedspin forming process for forming vitrectomy probe 10. Tubular needlestock 100 is disposed within a collet 102 of a lathe (not shown) in theconventional manner. Collet 102, and thus needle 100, are rotated athigh speed as indicated by arrow 104. A tool 106, having a generallyflat distal surface 108 with a generally spherical projection 110, isbrought into contact with an edge 112 of a distal end 114 of needle 100,as shown in FIG. 4B. Tool 106 is moved across the entire face of distalend 114 from edge 112 in the direction of arrow 118. Alternatively, tool106 is moved across the face of distal end 114 from edge 112 to slightlypast a centerline 116 of needle 100 in the direction of arrow 118, asshown in FIG. 4C. The force of projection 110 contacting distal end 114of needle 100 causes displacement of the material forming needle 100.When projection 110 reaches centerline 116, distal end 114 of needle 100is closed so as to form distal end 16 of probe 10. The diameter ofspherical projection 110 is preferably +/−ten percent of an outerdiameter of needle 100. Flat outer surface 16 a is preferably machinedto have a radius or chamfer on its periphery to facilitate pars planaincision.

FIGS. 6A-6C schematically illustrate a preferred, resistance weldingprocess for forming vitrectomy probe 10. Distal end 114 of tubularneedle stock 100 is brought into contact with a sheet of stainless steelfoil 150, and a compressive force indicated by arrows 152 is placed onneedle 100 and foil 150. Foil 150 preferably has a thickness of about0.004 inches. An electrode 154 is disposed on a side of needle 100, andan electrode 156 is disposed on foil 150. An electrical impulse is sentbetween electrodes 154 and 156. As the electrical impulse moves fromneedle 100 to foil 150, a localized area of high resistance isencountered that generates heat and welds distal end 114 to foil 150 ina melt zone 158. Needle 100 is disposed in a punch die 160, and needle100 is then punched through foil 150 (as shown in FIG. 6C) so thatwelded foil tip 162 forms distal end 16 of probe 10. A preferredresistance welding machine is the Model 125 resistance welding machineavailable from Miyachi Unitek Corporation of Monrovia, Calif. A microwelding head available from Miyachi Unitek Corporation, which containselectrode 156, is preferably used with the Model 125 resistance weldingmachine. A preferred weld cycle is a dual pulse cycle within the tenpercent (10%) to sixty percent (60%) power range. Flat outer surface 16a is preferably machined to have a radius or chamfer on its periphery tofacilitate pars plana incision.

From the above, it may be appreciated that the present inventionprovides improved apparatus and methods of performing vitrectomysurgery. The present invention is illustrated herein by example, andvarious modifications may be made by a person of ordinary skill in theart. For example, although the present invention is described herein inconnection with a vitrectomy probe, it is applicable to other ophthalmicmicrosurgical probes and non-ophthalmic micrsosurgical probes. Asanother example, although the present invention is described herein inconnection with a cutting probe, it is also applicable to an aspirationprobe.

It is believed that the operation and construction of the presentinvention will be apparent from the foregoing description. While theapparatus and methods shown or described above have been characterizedas being preferred, various changes and modifications may be madetherein without departing from the spirit and scope of the invention asdefined in the following claims.

1. A microsurgical probe, comprising a tubular body having an innerbore, a port providing access to said inner bore, and a closed distaltip, wherein said distal tip has a flat inner surface.
 2. The probe ofclaim 1 wherein said distal tip has a flat outer surface.
 3. The probeof claim 1 wherein said distal tip has a flat outer surface having aperiphery with a radius.
 4. The probe of claim 1 wherein said distal tiphas a flat outer surface having a periphery with a chamfer.
 5. The probeof claim 1 wherein said flat inner surface allows a distal end of saidport to be disposed a distance of about 0.006 inches to about 0.016inches from said outer surface.
 6. The probe of claim 5 wherein saiddistance is about 0.006 inches to about 0.011 inches.
 7. The probe ofclaim 5 wherein said probe is an ophthalmic microsurgical probe.
 8. Theprobe of claim 7 wherein said probe is a vitrectomy probe.
 9. The probeof claim 8 wherein said distance allows a surgeon to dispose said portcloser to a retina without contacting said retina.
 10. The probe ofclaim 5 wherein said distance allows a surgeon to dispose said portcloser to a target tissue without contacting said target tissue.